


gravity

by sweetie (Marnie)



Category: Shingeki no Kyojin | Attack on Titan
Genre: Alpha Eren Yeager, Alpha Levi (Shingeki no Kyojin), Alpha/Beta/Omega Dynamics, Alternate Universe - Canon Divergence, Anal Sex, Blow Jobs, Come Eating, Cunnilingus, Flirting, Intersex Omegas, Knotting, M/M, Mating Bites, Mating Cycles/In Heat, Multi, Multiple Orgasms, Non-Traditional Alpha/Beta/Omega Dynamics, Omega Armin Arlert, Omega Mikasa Ackerman, Pack Dynamics, Polyamory, Polyamory Negotiations, Spoilers up to Chapter 107, Threesome - M/M/M, Vaginal Fingering, Vaginal Sex, smut with a bit of plot because i can never just write smut, vignette style
Language: English
Status: Completed
Published: 2018-07-12
Updated: 2018-07-14
Packaged: 2019-06-09 00:39:22
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 8,372
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15255576
Author URL: https://archiveofourown.org/users/Marnie/pseuds/sweetie
Summary: “How do you feel about Captain Levi?” Eren asks him, over dinner.Strangely and suddenly anxious, Armin answers a question with a question. “How doyoufeel about Captain Levi?”“I care about him,” Eren says, without hesitation.“Good, so do I.” Armin sputters, pushing brussels sprouts around on his plate with laser focus.“I think he cares about you, too. I think he cares about you a lot.”“He cares about all of us,” Armin protests, weakly.--A simple haircut changes things between Armin, Levi, and Eren.





	1. cupid hit me, cupid hit me with precision

**Author's Note:**

> that spoiler tag? you should definitely heed it! you will be both confused and spoiled if you read this without being caught up!  
> the most recent chapters of snk kinda have me in a creative tizzy, so this fic was written up as a result of that. this whole thing is nearly finished, i just split it up into two chapters because i felt it was getting a bit lengthy. this chapter is negotiations and ust--the next is smut, and is where all of those spicy tags come from. it will be posted after i do some more editing.
> 
> for context, this takes place during the four-year time skip after the battle of shiganshina district and eren going to marley. these specific events take place in the year leading up to eren leaving for marley (so the main little ensemble is eighteen at the start of this and nineteen by the end of it)

The years following Shiganshina’s reclamation have not been easy.

They’ve reread Dr. Jaeger’s texts front to back and in between the lines, built a rough timeline of events that has three possible truths, and trained relentlessly. Eren shifts into his titan on the daily, and soon, the strain seems to drain the anger from him. Armin shifts as well, and the strain for him is worse. Those first few weeks, a shift leaves him bedridden each time he tries it, ratcheting Eren’s protective streak up with each occurrence. He’s gentler and more attentive than he’s ever been, and spends a lot of his free time watching Armin and Mikasa from afar. When their gazes meet, he smiles, with such tender warmth that it makes Armin’s chest hurt.

He brushes Armin’s hair behind his ears during conversation, and makes sure that he is comfortable when they are all winding down for the day. Did he want pillows? Did he want to switch chairs? Did he want to play chess, or just find Mikasa and cuddle in a pile, like they did as children? Jean starts calling him a puppydog, and Armin secretly agrees, but he doesn’t mind. He encourages it, and allows himself to revel in the attention.

Kissing Eren under the stars feels like inevitability, somehow, and the hurried lovemaking that follows leaves him crying through the orgasm washes over him like a wave. Eren is warm on his front, between his thighs, cock heavy and hard and _right_ inside of him, hitting some aching spot he didn’t know existed. It feels like the universe is drawn down to the two of them and the air between them, Eren’s long jacket on the ground the only thing separating them from whispering their secrets into the Earth.

“Are you okay?” Eren breathes onto his neck, sweat beading on his forehead with the effort of stilling his thrusts.

The worry in his eyes is so endearing that Armin can’t help but crane his neck up for a kiss, which Eren returns without hesitation.

“Yes, I’m okay. Don’t stop, don’t stop.” Armin gasps out, fingers curling into Eren’s long hair.

He comes again when Eren groans and locks inside of him, fingers clumsy but deliciously calloused on his clit, and the world makes sense yet again.

* * *

 

Levi would sooner chew rocks than admit it, but he is fond of their little pack.

Armin can tell because the heat in his caustic words is gone when the captain addresses him, just like it is when he speaks to Hange. He cares for the 104th, of course. But he bullies Armin into reasonable sleep schedules and cleans his working spaces. He goes out of his way to pull Eren into one menial activity or another when he’s getting too deep into his head to do things outside of training and planning. He trades techniques with Mikasa in the mornings and under the cover of nightfall, the two of them pouring over their gear and speaking in hushed tones.

Armin and Eren are “Brat One” and “Brat Two” respectively, with Mikasa they are “brat unit”, and Levi Ackerman loves them.

Armin loves him, too, and probably more than he should.

 

* * *

 

“You two are starting to look like each other. It’s creepy.”

“How do you mean?” Armin hums, distractedly. He doesn’t need to ask for clarification to know that Captain Levi is speaking about Eren. The recent development in their relationship had come as a surprise to absolutely no one, and though they faced gentle teasing for it from the corpsmen and a gentle lecture from Mikasa, not much has changed. The Marleyans in their care, already scandalized enough by the way secondary genders are handled on the island, are a bit less kind. Armin is confident, however, that thing will change in the future.

They are arranging a formation for practice with the thunder spears, heads bowed over a paper with roughly drawn stick figures representing each corpsman in their regiment.

“The hair. It’s getting so long, both of yours,” Levi fusses. “How are you going to watch out for yourself in the field? You need to cut it.”

“Can you do it?” Armin asks, unthinkingly. “Your haircut always looks well-done.”

He has always been good with his words, and usually considers every possible combination of what he wants to say to others before he actually speaks up. But this question just felt natural, and now that he has blurted it out, he can’t take it back.

He winces and looks up at Captain Levi. To his surprise, the alpha is giving him a considering look.

“I can.” He says. The tone of his voice rises towards the end, almost like a question, but is ultimately spoken with enough finality that Armin is sure the idea has been planted firmly.

“Okay. Please cut my hair.” Armin says.

Captain Levi stands and says, “Follow me.”

“You’re going to do it _now_?”

“Why the hell not?”

His quarters are as sparse as Armin expected them to be. Not a thing is misplaced. His bed is neatly made, a small stack of books are on his desk, organized by size. His bedroom is unremarkable, save for his spicy scent, which lingers in every facet of it. Armin breathes through his mouth, not sure how to cope with the frisson of heat that dances down his spine when he breathes it in for the first time.

Unsurprisingly, Levi has an array of razors and shears in one of his desk drawers. After drawing the windows, he gestures for Armin to take seat at his desk chair.

“How short do you want it?” Captain Levi murmurs, fingers trailing through the locks, now shoulder-length. His knuckles brush against Armin’s cheek, too long for it to be an accident.

“Shorter than it was before.”

Levi lets out a contemplative noise, deep in his throat. It is a distinctly alpha noise—he has heard Eren making the same noise when someone scratches his scalp—and weirdly comforting to hear. There is shuffling behind him, and soon Levi’s cravat, smelling deeply of him, is draped around his shoulders and the cutting begins. Levi cuts layers of his hair, at what must be incredibly precise angles, because he pauses and adjusts and snips and hums.

Before long, Levi is briskly swiping the stray hairs from Armin’s shoulders and saying, “Now you don’t look ridiculous.”

Armin reaches up to feel his hair, and is oddly but pleasantly surprised to feel that it is nicely shaped, framing his face.

“Thank you,” Armin says.

“You’re welcome. Now go to sleep, brat. I saw you nodding off earlier.” Levi commands, removing his cravat from Armin’s shoulders with a cursory shake of the fabric. Armin will smell like hm for the rest of the day.

Later, Eren uses his spare key to slip into Armin’s room. He catches sight of Armin’s hair cut and startles, his brows climbing his forehead.

“Do you like it?” Armin asks, nervously reaching up to touch the back of his exposed neck.

Eren slides under the covers, entwins his legs with Armin’s, and kisses his cheek. Armin turns his head and catches his lips in a proper kiss, and he can feel Eren smile into it.

“I’ll miss braiding your hair, but I like this. I can actually see your face.” Eren kisses his forehead. He breathes in Armin's scent as his arms curl around his waist. He stills, for just a moment, and then relaxes.

They speak of other things, and do not address the question lingering in the air.

* * *

 

For Eren and Mikasa, finding their way to Armin after an injury is second nature. After her practices with Levi, Mikasa finds him and shows him every injury or scrape or bruise she sustains. He tuts and clucks over her, warning her not to overexert herself, but he knows that he has no room to complain in his current situation. He is thankful for what is between them, this quiet comfort.

After one especially long time spent flying about the woods ends with both her and the Captain covered in miscellaneous wounds, she brings him along to Armin’s room.

She knocks, and Armin holds up a finger to signal for silence, pointing at Eren, who has settled down for a restless nap on Armin’s bed. He’d come to keep Armin company as he reviewed plans for the future of the 104th, something Hange had been having him do with increasing frequency in the coming days. Hange has never been subtle about their plans to have him take command one day. Maybe this is his penance, for Commander Erwin’s life.

“Captain Levi needs to be seen to, as well. He’s not happy about it, but he does.” Mikasa whispers, lips tight with frustration.

“Are you both okay?” Armin frets.

“Peachy,” Captain Levi hisses, brows low with irritation.

He’s never been particularly shy about his status. Armin doesn’t know much about Captain Levi’s past, but he has an accent that sounds more distinctive than all of theirs, even those from providential little places like Shiganshina, or Sasha’s home village. He never attempts to mask his alpha scent, and he’s not shy about using his strength to his advantage. In this moment, Levi is so angry that his scent broadcasts the emotion like so many little pins and needles on the skin. It sets Armin on edge, makes him want to tilt his head, or crowd himself underneath a nest.

There is absolutely no hope of Eren staying asleep now. He has always been sensitive to scents. He wakes with a discontented little growl, and Armin allows himself a moment to close his eyes, pained. There’s no telling when Eren will get sleep again.

Mikasa touches his arm, drawing his gaze to her. “I’m sorry,” she says, her face one of genuine regret. She worries about Eren more than anyone.

She approaches the bed, where Eren has pulled himself up into a seated position and is peering at them from behind his fringe with narrowed eyes. Once he fully processes the situation, the tension in his shoulders eases.

“Captain.” He says by way of greeting, eyes fluttering closed in contentment when Mikasa reaches out to smooth his fringe away from his face with a small tsk. He pushes his head into her hand, affectionately bumping his forehead into her hip.

“Brat Two,” Levi says. He is still frustrated—that much is visible by the set of his shoulders—but he has the decency to reign in his scent, the closest thing to an apology they will get. “I’ve been invited to this meeting of the brat unit because your little packmate doesn’t know how to control herself.”

(Never mind that Mikasa is taller than both Levi and Armin. Levi brings everyone down to his level, somehow.)

Giving a proud little smile, Mikasa says, “I won the sparring match this time around.”

The news is enough to ease some of Armin’s worry. “Really? That’s great, Mikasa. You’re getting so much better these days.”

Levi sighs. “Can we get this over with? I’m hungry.”

Before long, Armin has his modest first-aid kit prepared, and Levi has shed himself of his cravat, jacket, and shirt. Armin knew that, logically, serving in the Survey Corps requires a certain level of strength. He’s still surprised by the whip like muscle making up his compact form, and by the tapestry of faded scars on his pale skin.

There’s a story in the pale pink slash along his neck (is that what the cravat for, he wonders, cheeks flushing in remembrance) and the near perfect circle of puckered flesh on his shoulder. Dozens of little scars are littered about his body. Armin is curious about his back.

Mikasa has added marks of her own to Levi’s skin, on his arms and chest. Very few of them will scar if he treats them well. He tells Levi as such. The alpha waves his hand and says, “It doesn’t matter. I just don’t want them infected.”

He’s notoriously fussy about cleanliness, and Armin gets the feeling he’s going to critique Armin’s capabilities as a medic. Instead, he watches with unwavering interest as Armin cleans each wound, dabbing them with alcohol and healing balms. When his gaze shifts from his wounds to Armin’s face, it feels heavy.

Eren and Mikasa are talking softly on Armin’s bed, but every now and then, they will fall silent, and the odd tension in the room rises. In these moments, Armin fumbles to ask questions about this or that, knowing full well that Captain Levi detests small talk.

Finally, his wounds are completely treated, and he is properly wrapped in bandages and plasters. Armin insists on helping him back into his clothes, which he agrees to with his characteristic grumbling and no physical resistance. His skin is warm where Armin’s fingers graze against it, though he does his best to minimize this. When they're done, Levi tells him to hold on, and fixes him with an appraising look.

“The haircut suits you, Arlert.” He says, with an air of satisfaction.

Inordinately pleased, and also tad nervous, Armin reaches up and tucks a lock of his hair behind his ear as he stutters out a word of thanks. Eren does it to him so often that it has become something of a self-soothing habit, so he was glad that the haircut left enough of his hair left for this tradition to continue.

Captain Levi follows the motion, his gaze flickering down to Armin’s smiling lips before they meet his eyes.

“Good night, brat unit.”

Then he is gone, closing the door softly behind him.

Armin lets out a relieved sigh, and beckons Mikasa over to the space he occupied. The look Eren gives him over her shoulder is uncomfortably knowing.

 

* * *

 

“How do you feel about Captain Levi?” Eren asks him, over dinner.

Strangely and suddenly anxious, Armin answers a question with a question. “How do _you_ feel about Captain Levi?”

“I care about him,” Eren says, without hesitation. He’s got that curiously owlish look on his face that spells trouble in the form of mischief and boundless willpower.

“Good, so do I.” Armin sputters, pushing brussels sprouts around on his plate with laser focus.

“I think he cares about you, too. I think he cares about you a lot.”

“He cares about all of us,” Armin protests, weakly.

Eren reaches out and takes his hand, callused fingers worming their way between where they’ve curled against his palm.

“It’s okay,” Eren says.

Armin open’s his mouth to protest, but then Sasha and Connie are bounding over to their table with their plates piled as high as Nicolo will allow (a bit more for Sasha, who he is deeply smitten with). Jean follows, pulling up a chair. Mikasa takes her usual place behind Eren’s back, her hand absently finding a place on his shoulder.

“Ugh, you guys are so much.” Jean complains, giving the three of them a sweeping look of disgust. “You’re always all over each other! I know you’re a pack, but this is where we _eat_.”

“You’re just jealous,” Connie snorts. Sasha, intent on her meal, speaks her agreement around a mouthful of food.

Armin shares an exasperated look with Mikasa as Jean immediately starts an argument, ever contrary.

Eren squeezes his hand, and Armin squeezes back.

The rest of the regiment pours into the dining hall. Armin watches as Eren catches someone’s eye and nods. He looks over his shoulder, catching the gaze of Captain Levi, who tilts his head at him. Armin chances a little wave, stomach fluttering.

 

* * *

 

Armin has a hypothesis to test.

 

* * *

 

One half of the test comes in the form of observations:

He finds several excuses to bring Levi and Eren into the same space. It is not hard to coax Eren into keeping him company for the day, and the higher ups are all accustomed to seeing their two titan shifters in each other’s company.

There’s a hesitance in the way Eren acts around Captain Levi. There always has been, ever since their first meeting. He’d been told the only time Eren abandoned his characteristic tentative attitude towards Levi was during that fateful day in Shiganshina, when he'd thought Armin's life was forfeit.

As the days pass, Armin realizes it’s because Eren defers to Levi, even beyond the simple chain of command. He does not sit until Levi sits, generally does not speak unless addressed, and he is quick to comply with whatever little errand Levi sends him on during their less confidential meetings. On those days when Eren is pushed from the rooms and meeting halls, he waits for Armin outside of the door, but he never walks Armin away to his next destination he is sure Captain Levi has exited the room as well.

Captain Levi begins to bully Eren the same way he does Armin, demanding he take rests and eat, lest he waste away in body as well as mind. He calls Eren every name under the sun, but it never sounds like an insult. He watches Eren as much as Eren watches him, and sometimes, they make a competition of it, only ceasing when Armin exasperatedly draws their attention to him.

 

* * *

 

The other half of the test comes in the form of actions:

Armin leaves the top button of his shirts undone some days. Captain Levi glances at his neck at least three times each conversation. (Eren does the same, with a lot more frequency, and later confesses that it drives him to distraction.)

Armin does less to hide his scent. This draws the attention of everyone close to him, really, but what matters is that Captain Levi makes an absentminded, heatless complaint about sweet cologne in the middle of another first-aid session. Eren coughs, and Mikasa smirks.

(“I hope you know what you’re doing.” She tells him.)

He tries asking for things, too. Some requests—combat training—are flatly refused, while others—regular hair cuts, and a tentative offer to join in on the days when Armin reads fantasy novels to the 104th after dinner—begrudgingly agreed to. In turn, Captain Levi asks that Armin reviews his reports, confessing that he had not learned to read or write until he joined the Survey Corps. The admission is casual, but there’s a tension in his stance that tells Armin it took a lot of courage.

Finally, he does the same little things he does when he wants to draw Eren’s attention. He stands a bit closer to Captain Levi’s side, and finds every excuse to crane his neck, or brush against him. He even plays at clumsiness, tripping over his feet and walking dangerously close to walls. Each time, Levi will grasp his wrist and pull him away. Once, he genuinely does slide over papers scattered on the floor, and Levi catches him with a strong arm around his waist, palm warm on the curve of Armin’s hip. He removes his hand as if burned when Armin unconsciously moves into his hold, and avoids eye contact for the rest of the day.

 

* * *

 

“You’re being mean.” Eren observes.

It’s the first admission that Eren knows what he’s up too, and it takes him off guard.

“Maybe you’re being too nice,” Armin says, primly.

Then, the false confidence leaves him, and he takes Eren’s hand.

“Is it really okay?”

“You know I would tell you if it wasn’t.”

An ache Armin was unaware of is lifted from his chest.

 

* * *

 

“We can’t keep doing this,” Levi growls, after spending a good three minutes stealing glances at Armin’s exposed skin during a late night grammar lesson. Knowing that they would be working together, he'd worn one of Eren's forgotten shirts, hoping that it would fall off of his shoulder with every movement. It did.

“It is pretty late,” Armin replies, weakly. He flinches when Levi levels him with an unimpressed look.

“I think I’m gonna let you sleep off your little lapse.”

In the morning, Armin and Eren are called to Levi’s office for a short meeting.

“Captain Levi,” Armin begins, “I think I know what this is about—”

“Shut it.”

He gives Levi a hesitant glance before taking a seat in the chair placed in front of Levi’s desk. The Captain is leaning against it with his arms crossed over his chest. Eren stands behind his chair.

“We should apologize.” Eren says.

“We never wanted to make you uncomfortable! It’s just, I thought—well, we were thinking—"

“I said shut it, brat,” Levi growls. “ugh, you really make me sick, sometimes.”

Armin smiles, giving him a wobbly grin. “Only sometimes?”

“Only sometimes,” Levi agrees, and pulls him in for a kiss.

Armin presses into him, feeling vindicated and warm. When Levi pulls away, he weakly chases his lips before giving up with a little sigh of defeat, his forehead resting against Levi’s neck.

Levi strokes his back, brisk but comforting. Eren draws near, and Levi pulls him down by his collar for a less gentle kiss. Eren follows his guidance with the sweetest sound of interest, igniting heat in Armin’s belly.

“You two are going to be the death of me.” Levi announces, to no one in particular. His lips are tantalizingly pink.

Eren lets out a rare laugh, and Armin bashfully pushes his hair behind his ear. Then, realizing that his ears must be red, he undoes the action, biting his lip.

“You don’t get to be shy now, Armin.” Eren teases him, gently.

This time, it’s Levi who does the honor of tucking his hair behind his ear. The look on his face is terribly fond.

“I’ve been wanting to do that,” he admits.

Armin kisses him again.


	2. i wonder if you look both ways when you cross my mind

**Notes for the Chapter:**

> :)  
> hello! this chapter is coming to you a little late because it's summer, i live in the south, and i'm being oppressed by bugs in my own home! homeofobia never sleeps i see!

There is something precious in the softness of Armin Arlert.

He is no pushover, to be sure. He’s a terror with a gun, and dangerous when given time to plan. And now, with the power of the Colossal Titan residing within him, he is a veritable weapon. Despite this, he’s retained a fairly demure nature. He’s all polite smiles and considerate suggestions, and with Levi, he’s hair tucked behind ears and hesitant hand holding. He can carry his own books, and he knows good and well when his body is being pushed to its limits, but he allows Levi to fuss over him anyway—seems to revel in it, if the blushing cheeks and bitten lips are any indication.

But he’s no angel, and Levi has learned this well, over the months. The young man is plays into his strengths with cheerful efficiency, leaving his buttons undone and, today, coming to a meeting with kiss-bitten lips. He looks at Levi from underneath his eye lashes, smirking when he knows he has Levi’s attention.

Levi gives him a look that hopefully conveys the amount of trouble he is in, but the kid probably takes it as a challenge.

When their meeting is over, Levi takes his wrist and guides him to his office, ignoring Armin’s worried little questions. He has half a mind to scold the kid, but what he ends up doing is telling Armin to strip.

And Armin smiles, small and satisfied, like this is what he wanted all along, and undoes his long overcoat.

Since he has become a part of Eren and Armin’s life, Armin has taken to wearing a cravat as well, usually in coral pinks and baby blues—colors that bring out his eyes and the color in his lips. When he removes it, Levi immediately notices that there are markings on his skin, and that he is not wearing a shirt. More buttons are undone, revealing more flushed, naked flesh. He is wearing the knee-high utility boots that every soldier is required to wear, and nothing else.

When the overcoat slides from his flesh and onto the floor, his smell hits Levi like a veritable wall. Clever—he’d sprayed the overcoat with scent blockers.

Levi growls. Armin gives him another sweet smile and jumps up onto his desk, crossing one slick thigh over the other.

“I’m going to kill Brat Two.”

“Before you punish Brat One?” Armin asks, raising a brow.

He lets out a sound suspiciously close to a giggle when Levi crowds into his space, plays at resistance when Levi pulls at his knees. In the end, his thighs fall open, almost obscenely wide against Levi’s desk. He smells of Eren and his own arousal, and when Levi kneels, he can see a trickle of cum spilling from between flushed lips.

“Eren had to practice with Commander Hange,” Armin is saying, bringing Levi out of his haze. “I wanted him to be able to relax, but we didn’t have the time for me.”

And that does something to Levi’s alpha, makes his brows furrow and his chest tight, fueled by the need to satisfy and provide.

“That little shit,” Levi fusses.

“He wanted to get me there, but he was going to be late. I told him I wanted to do it with you.” Armin explains.

And Levi is still angry, probably more angry than he should be, but there are pheromones in the air and Armin is bucking into the exploration of his fingers with small little whines of need. Levi delves his thumbs into the swollen lips of his cunt, and pulls them apart, exposing his pink flesh to the air. He blows on him, crooning when Armin’s hips give a strong jerk in reply.

“I’m here.” Levi says, and then he leans in to lick a slow path on Armin’s twitching core from cunt to clit. Armin follows the motion with a hiss and rolling hips, one hand coming forward to rest in Levi’s hair.

Eren’s spend is heavy on his tongue, mixing sweet with Armin’s arousal where he dips his tongue into Armin’s hole.

“Captain,” Armin whimpers. His free hand has traveled down to his flushed cocklet, pulling quick and dirty. Levi allows him to have his, flattens his tongue and lets him fuck himself on Levi’s tongue until he’s whining through an orgasm. Levi slides two fingers inside him, thrusting through his contractions.

When he’s caught his breath, Levi pulls away and asks, “Okay?”

“Perfect,” Armin says, brushing Levi’s fringe away from where it’s flattened against his skin with sweat.

“Good.”

Levi presses his face back into Armin’s folds, hands stilling his hips when he tries to arch away.

“It’s too much,” he chokes out. Levi ignores him, reaches up to pull the hood away from his clit, fasten his lips over it, and suck. Armin sobs, and when Levi begins trailing shapes onto the little nub with his tongue he nearly falls silent. Levi watches him squeeze his eyes shut, tears falling down flushed cheeks. His hips are moving with no apparent rhythm, sometimes moving close, sometimes startling away. He flushes so lovely when he’s like this, all the way down to his chest. Levi reaches up to tweak one of his pebbled nipples, and Armin’s silence is broken with a hitching little gaps as he comes again, wetness gushing down Levi’s chin.

After a moment, he pushes Levi’s head away, still trembling.

“You’re filthy,” he croaks.

“It’s your fault.” Levi tells him, raising a brow.

There’s no way he can get rid of it all, but he licks some of his own slick from Levi’s face anyways, tongue hot against his skin.

Then he slides off Levi’s desk and kneels, pressing his face into where Levi’s erection is straining against his pants.

“Can I?” He asks.

“ _Yes_.” Levi answers, more emphatically than he means to.

Armin smiles, and undoes his buckle with practiced efficiency. He pulls Levi’s pants down far enough to cup his balls. Armin licks up the seam of them to the root of his cock, working his way to the tip with wet little kisses. He takes the head into his mouth, working his tongue against it, before swallowing Levi down as far as he can.

“Armin,” Levi pants.

Armin’s eyes snap up to meet his, and then the wet heat around his cock is rippling as he swallows, gently. What he can’t reach, he pumps with his hands, twisting the way Levi likes it on the downstroke. His lips are tantalizingly red where they pull against his shaft. He drags his head back, cheeks hollowing. He starts a quick, shallow rhythm, obviously intent on bringing Levi off. He would love nothing more than to come down the omega’s throat, to see those pink lips painted white. But there’s a desk behind them, an opportunity, and little time.

“Stop,” Levi tells him, cock jumping at the complaintive noise Armin hums against his flesh. “I’d rather come inside you.”

Armin pulls away, fingers playing at where Levi’s knot is starting to form at his base.

“I’d like that.” He says, voice deliciously hoarse.

“Do you feel okay?”

“Mmmhmm.”

Armin stands, and with a supine little stretch turns his back to Levi, situating his feet shoulder’s width apart. With his hand curled over the edge of the desk, his back arches in a gorgeous presentation, his golden hair fanning lightly against his neck. It needs to be trimmed. Levi brushes it aside and presses a kiss onto the back of his neck, close to his scent gland.

Levi gently kicks at the omega’s feet, running a soothing hand down his back when Armin lets out an inquisitive noise and widens his stance. Were Levi less desperate for him—and if they had more time—he would tease, trail the head of his cock through his folds and against his flushed erection. Instead, he lines himself up and slides home with a growl. Armin’s answering moan is low and guttural, settling some of the restless instinct in Levi’s chest as he grasps his hips and begins fucking into him, quick and hard.

Armin is whimpering desperately into the desk, probably a little too loudly to be decent, despite its muffling effect. One of his hands releases the desk to reach between his legs, fingers working curiously over his clit. A wrecked sound tumbles from Levi’s lips at the answering flutter of Armin’s walls. His rhythm falters, hips jerking forward harshly, and then Armin is keening through an orgasm that Levi fucks him right through. He knows that Armin’s cock has probably pumped his spend all over his desk, and his scent will linger even after Levi scrubs it clean, driving him to distraction when he should be working.

“Please,” he says, rolling his hips into Levi’s thrusts as well as he can with his legs locked around Levi’s strong ankles.

Levi can feel him riding the wave of one release straight into the next one, and he has the sense of mind to angle his thrusts just so, bucking deeper until Armin calls his name and clenches down tight. And Levi wants to knot him, he does, but they’ve got work to do and a people to save, so he curls his own hand around his knot and presses his forehead between Armin’s shoulder blades and comes like a shot, the breath punched from him.

“Fuck, Armin.” He gasps out, one hand absently stroking the omega’s trembling side.

“You did,” Armin points out, sounding decidedly punch drunk.

Levi lets out an incredulous chuckle, unable to help a smile at Armin’s answering laugh.

They rest for a moment, Levi pressed into his back. The faint sound of conversation outside his door eventually rouses them. Armin hisses softly when Levi pulls out. Levi pulls a neatly folded handkerchief from his pockets and uses it to clean him up as best as he can. When he’s done, Armin turns around and leans in for a kiss. Levi can taste himself on Armin’s tongue when he sweeps inside, and though he’s satisfied for now it is still deeply arousing.

“Thank you,” Armin says.

“No, thank _you_ for cleaning my desk.” Levi tells him, smiling against his lips.

Armin gives him a playful shove, melting into him when Levi locks his arms around his hips and brings him in for a gentle embrace. Armin rests his cheek against Levi’s forehead with a sigh.

Eventually, once they are as clean as is possible, Armin actually does clean Levi’s desk. He’s smiling the whole time, though, and when they lock gazes, his cheeks flush. If Levi does his best to draw Armin’s gaze, well, that is their secret.

 

* * *

 

Levi and Eren are hesitant around each other.

Eren has always been privately cowed by the older alpha. In the early days of their training as cadets, Eren was notorious for being hotheaded and hard to direct.

Armin supposes that for Levi, it is a bit hard to decide what to do with someone who was so open about their respect with him, with none of the fear that usually comes with it.

Eren has calmed over the years. He listens, and he watches, in all things. He learns that Levi likes holding them, even though they are both taller than him and growing still, and that he is the one who sneaks honey into Hange’s tea before it finds its way to their desk. He learns that Levi spends most nights sleeping upright at his desk, and that he likes to cook in his free time. Eren indulges all of these in his own understated way, chasing Levi’s rare smiles with the same endearing focus Armin had fallen in lov

It carries over into the bedroom. Neither of them had ever been with another person before each other, but Eren learned Armin’s body quickly, learned where to kiss and lick and suck to drive him up the wall.

He learns Levi just as quickly. He learns that Levi is has a ticklish spot on his inner thigh, and that he has a biting habit. He learns that Levi likes to savor the feeling of Eren's lubed fingers inside of him, the burn of the stretch and the brush of his finger against the sensitive spot deep inside. They've spent many days curled into each other, exploring and murmuring words of love and devotion into each other's skin. 

Armin is particularly delighted to learn that he likes being held down, Eren's hands tight on his wrists as he slides in, whispering encouragement into the air.

"Is it good?" Eren asks, pushing in at an angle Armin knows from experience is painfully good.

Levi lets out a small sound in answer, pressing a kiss onto Armin's hand when he strokes his cheek, fascinated by the play of pleasure and emotion on his face.

"Shut up and fuck me," Levi tells him. He tries to meet the slow rhythm Eren starts, but Eren stills his movements, and Armin can see the exact moment Levi melts into his hold, helpless with arousal.

He comes into Eren's hand, gasping for air into the blankets. And taking a knot will never satisfy an alpha the way it does for an omega, not really, but he Armin cherishes the moments where they are linked together, with Eren pressing lazy kisses into the knobs of Levi's spine and Levi sighing into Armin's hands.

Armin wants nothing more than to protect them, and these moments.

Whatever danger lies beyond the walls is not worth Levi's smile or Eren's laugh.

 

* * *

 

Armin is usually the last person to know when his heat is coming.

For Eren, telling when Armin’s heat is near is as easy as breathing, literally. Armin's soft scent, like faded pages and sweet bread, turns heady, broadcasts _hold me_. He's more susceptible to Eren's gentle commands than usual, sighs and agrees when Eren beckons him to bed instead of frowning and arguing about deadlines. When Eren strokes his neck, he lets out a low purr and thoughtlessly directs his hands to one aching spot or another. When Eren brings him food, or helps him carry books, or any little such thing that he'd do on any other day, Armin's gratitude is almost a physical force, igniting a low heat on his skin.

It's kind of shameful, but Eren likes when things take this turn. He likes Armin indolent and trusting. They've been with each other for long enough that their relationship is a comfortable and supportive push and pull, and the addition of Levi only seems to cement that. With the two of them there to provide and protect, some of the agitation lingering at the back of Eren's mind is settled. He can forget about the walls, and the danger across the sea, and remember that those close to him are safe.

It’s especially sweet to see the way Levi handles Armin as he is under the daze of pre-heat. Armin is kind-hearted, but as the years have passed—after he has been forced to shift into a titan so often, along with shouldering the growing responsibilities he has as Hange’s candidate for the next Commander—his tolerance for being told what to do has been all but erased. The first time Levi tells him to go to bed and he actually agrees, planting a kiss on his cheek before pattering away, Eren hadn’t been able to hide his laughter. He has rarely seen Levi express surprise, but and he has never seen his eyes quite so wide.

“He’s going into heat.” Eren explains, one night. Armin has burrowed happily into Levi’s bed, a hasty nest of their jackets and Levi’s pillows assembled around his head. When he’d first seen Armin’s particular nesting habits, Levi fretted that he was unable to breathe. Now, he looks upon him with that fond expression reserved only for the two of them.

“He looks stupid.” Levi says.

Eren laughs, reaches out for Levi’s hand. Levi takes it, thumb running a comforting circuit over the back of his knuckles.

“It’s comforting for him. Just go along with it.”

So Levi does. He lets Armin wear one of his cravats after spending a day out in the heat, and does not protest when Armin rubs his wrist onto Levi’s. Their relationship has been something of an open secret for a time now, but it is truly no longer up for debate. Jean announces his disgust and frustration to the Eren and Armin over dinner. Connie congratulates them for “snagging one of the higher-ups”.

At Armin’s request, they spend some of their free time huddled together in a nest of his making. He likes being in the middle, and always smiles when he sees the two of them holding hands or touching somehow, inordinately pleased with their little family.

“I think we should bond.” Armin tells them, as they are settling into one for the night.

“Give me three reasons why you think that’s a good idea,” Levi hums, reaching out to pull Eren close. His hand is warm where it eventually rests, on Eren’s lower back.

Eren reaches up and tucks Armin’s hair behind his ear, and when he’s done he curls his hand around Levi’s wrist, anchoring the three of them in place.

“First, it’s practical. Once both of you has spent a rut together, we’ll be able to vague impressions of each other’s’ mental and physical states from afar. Also, I think it’ll help reign in your instincts and keep you from making rash decisions on the field. Finally, I want to. Eren?”

“I’ve been wanting to bond with you guys for a while,” Eren admits.

“What am I supposed to do with you brats?” Levi sighs.

“You could keep us.” Armin says, sounding sad enough that Eren lets out a comforting crooning noise, kissing the delicate skin behind Armin’s ear.

“I like that idea.” Levi says.

“Like you’d be able to get rid of us.” Eren laughs.

\--

In the end, Armin’s heat comes with little fanfare. He wakes up fine—if achy—on a Sunday morning, and is under the throes by nightfall. He has always been blessed with mild heats, and this one is no different.

Eren knots him until he falls asleep, and then Levi, and when he is spent, Eren brings Armin to orgasm with three of his fingers, cooing encouragements to him as he rolls his hips through the contractions, sobbing about how it isn’t enough.

“What do you need?” Levi asks him, hands gentle on Armin’s cum-smeared stomach.

“What you _promised_ ,” Armin all but hisses, immediately settling at Levi’s answering growl.

“He’s just hurting, it’s okay.” Eren says, rubbing circles on Levi’s back.

He can see the exhaustion settling into Armin’s eyes. “Armin, you need rest.”

“No, I just need you.” Armin whimpers, and he paints such a pitiful picture that Eren’s chest throbs.

“Later,” He says, sharing a look with Levi.

\--

Later is postponed by a full night’s sleep, and then Armin’s growling stomach.

It is early enough in the morning that it’s still dark outside. Armin hums contentedly when Levi brushes his fringe from his forehead, tutting about how he needs a bath, and then kicks his feet at them both.

“Cheese and grapes, please.” He says.

Eren catches his foot and presses a kiss into the arch of it, delighting in the high laugh that filters out from the small mound of pillows Armin has burrowed himself underneath.

Eren is amused by the visible relief on Levi’s face as the two of them make their way to the kitchens, illuminated only by a small candle on a tray. In the low light it casts, Eren can make out a wry little smile on Levi’s face. Levi does not smile often, and even less so when he is happy. It’s a lovely expression on him. Not for the first time, Eren reminds himself to find one of those strange Marleyan devices and capture Levi’s face in a moment.

“I’m glad you’re with us.” Eren tells him.

Levi rolls his eyes, and doesn’t respond. It is all but a vocal admission that the feeling is mutual, so Eren hides his smile in his hand.

“My first time helping anyone through their heat and now I’m signing my life away to you brats. Could be worse, I guess.” Levi says, at length.

\--

Levi’s rut sets in with the next wave of Armin’s heat.

Eren has never seen him like this. Even during sex Levi has a way of maintaining a neat sort of look, all straightened shoulders and clothes left folded on the nearest clean surface. (And when they don’t have the time to remove their clothes, there isn’t a fold or crease to be found. Eren is convinced it’s some sort of magic trick.)

But rut has Levi’s hair messy and his teeth bared when someone passes the bedroom door. Rut sets a flush that travels from his neck to his sculpted chest, and it makes him _mean_. He bites at the gland on Eren’s wrist with little hesitation, pausing to lick at the pink mark it leaves behind. It’s temporary—a promise. Armin presents to him, the tempting curve of his ass high in the air, and when Levi slides into him, the keen that he releases is subhuman, pulls at something within Eren’s own lizard brain.

Levi gives Eren a look of warning when he stands from the bed, but he settles when Eren sits down in front of them, pulling Armin’s head onto his lap. He is meant to serve as a comfort, really, and it works for a while—Armin cries sweetly onto his skin, hands curled tight around his thighs as he works back onto Levi’s thrusts. But after a while, he mouths at Eren’s sleep pants, mouths hot over his cock.

Eren does not fight him, lets him take Eren out and swallow him down, sucking him hard and fast and dirty, his moans vibrating against his flesh just so. When Armin comes, because his brows furrow and he moans around Eren’s cock. He comes down Armin’s throat, hands curled into his hair, and watches as Levi beats his fist against the mattress, thrusting deep.

Eren gently pulls himself from Armin’s lips, eyes drawn to the white trail of come left behind on his lips. He presses his face back into Eren’s thighs, raises himself up onto his knees, and rolls his hips back into Levi’s hold, fucking himself on the alpha’s knot.

Levi moves with him, his hand disappearing underneath Armin’s stomach. He’s pressing kisses onto the back of Armin’s neck, wet and disorganized. As Armin seizes up once again, he zeroes in on Armin’s scent gland and sinks his teeth in. Armin lets out a high whine, bucking in place. After a moment, Levi is kissing at Armin's neck with lips colored rouge with his blood, soothing the pain that must be burning there.

And once all is said and done, once Armin has fallen into an exhausted sleep, Levi gathers their shared juices from where they are joined and uses it on Eren. Eren lives for this, the ache of penetration, the feeling of Levi's thin fingers taking him apart. He's hasty with the lingering rut, swirls Eren's rim once before sliding in, fucking his spend and Armin's slick into him. Their shared pheromones have done a number on Eren, too, even though his rut has not set in. There's an ache in his gums and his balls are tight, and when Levi takes him in hand he hisses with how sensitive it feels.

"Levi," he says, burrowing his face into Levi's neck as he starts a punishing rhythm. It hurts, just a bit, but it is a good pain, Levi's cock hot and heavy inside. Levi bites at Eren's gland when he comes, and the bright burst of  _pleasurepain_ it sends rushing through his body sends him hurtling right into another orgasm so powerful tears are springing in his eyes. The spray of his come hits his chest and even his chin. There's a heat playing underneath his skin, something animal hungry, and when they finally lock together, Eren leans up and bites his own mark onto Levi's skin.

\--

Eren watches Armin sleep, trying his best to fight through the itch underneath his skin telling him to reach out, to fuck, to claim. At the barest hint of motion, though, he's pulling Armin close by the hips, hands reaching down to squeeze at where his cocklet is growing hard, and to the folds below, where he is already slick with need. Armin hums and obligingly spreads his thighs, rolling onto his back. Levi, who is resting on his stomach, leans on his elbows and kisses him, slow and filthy.

"It's his turn," He says. Armin whimpers into his lips.

If Eren were in a better state of mind, he'd do this differently. Slide his fingers inside and rub that spot that makes Armin gush, or put his mouth on him and lick him until he cries. He will do that later. Now, he rolls Armin onto his stomach, slides home, and chases his release with quick, shallow thrusts. Armin's cunt is clamping down on him, greedily milking an orgasm out of him. It's not enough, and though his knot is forming it isn't enough to lock them together. Eren pauses, stroking at Armin's hips and crooning low in his throat.

"Okay?" Eren asks.

"More," is his answer, rasped into the air like a challenge.

So he gives more, presses his omega down onto the sheets and fucks him hard, knowing that he can take it, that he wants it. He clenches tight when Eren pulls out, cunt fluttering acceptingly when he thrusts in, his cock reaching that rough area near the front with each roll of his hips. The bite comes before before the knot does, but when he finally thrusts his hips in and finds that he can't pull out, it makes the tang of blood on his tongue feel more final, and the tears rolling down Armin's cheeks feel sweeter.

Something shifts in Eren's chest, like some lost puzzle piece finding its place.

 

* * *

 

The Marleyan officer in charge of the wounded Eldian soldiers gives such a violent start at the sight of Eren's neck that he can't help but look up at the man, even though he has been doing his best to avoid eye contact with most people on this excursion.

"My god, what's that on your neck?"

"Bonding marks." Eren answers, genuinely confused by the look of disgust that settles onto his face.

He shakes his head. "You people, I swear. Animals to the core."

After the man scoffs and walks away, Eren asks an Eldian soldier about it, coming up with a flimsy excuse about being raised in another country's camps. The woman is missing a leg, much like Eren, and he feels absurdly guilty about the fact that he can create another one whenever he wishes.

"It's a bit uncouth to show our marks like that. They already hate that we do it in the first place, and you've got two." She pats his shoulder. "Just make sure your hair hides them until you can get a collar. I don't blame you for making those marks before you left for the field, though. I hope you get to see them again."

He will. Though he can tell she doesn't think he will, he is touched by the sentiment regardless.

Later, a young man adjusts his arm band, and flushes when he sees Eren's marks.

"I lost my collar," Eren says, fascinated by the look of relief that crosses the boy's face.

"I can get you a new one. I'll come visit you when I've got the time!"

His name is Falco. He's got a hodgepodge of scents lingering on his skin, a packmate if ever Eren has ever seen one.

Eren settles down to sleep on an uncomfortable mattress later that night, and reaches out for the nascent bonds at the back of his mind. He gets two answering pulls in response, mixed worry and love and reassurance, and is finally able to sleep.

(Later, days later, Eren feels the sting of Armin taking his titan form, and the hot pulse that accompanies Levi twirling about on the battlefield. It feels like coming home.)

**Notes for the Chapter:**

> hello again please share your thoughts with me if you have the time!!! i hope you enjoyed it!!!!
> 
> once again, i am my own beta reader, so if there are weird mistakes please let me know so they can be fixed. i operate on very little sleep
> 
> chapter titles came from the song [see you again](https://www.youtube.com/watch?v=EZE62LpaqHg) by tyler the creator and kali uchis!
> 
> edit: i made a tumblr, u should talk to me at [sweetfoolmarnie](https://sweetfoolmarnie.tumblr.com/)


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